Production process of silicon carbide brick

The formula for coarse, medium, and fine SiC should be 5:1:4. The raw material for manufacturing silicon carbide bricks is generally black SiC, with the following chemical composition: SiC 98.0%, free C 0.5%, Fe 0.2%, and free SiO2 0.6%. Due to different combination methods, there are differences in the manufacturing process. The brief process of different combination methods is:
(1) Silicon nitride combined with silicon carbide brick: A green body formed from coarse, medium, and fine silicon carbide particles and fine silicon powder, in pure N2 gas at 1370 ℃, produces a structure with% 26 α - SiC as the skeleton and% 26 α and% 26 β - Si3N4. Silicon nitride combined with silicon carbide bricks for the substrate. There are still a small amount of residual silicon and SiO2 in the matrix in the product, and the relative content of these components varies depending on the manufacturing factory.
(2) Combining silicon carbide bricks: SiC, silicon powder, and carbon powder are mixed and formed in a certain ratio, and fired in a reducing atmosphere at 1400 ℃. In most cases, buried charcoal firing is used. During the firing process, a% 26 β - Si3N4 bonded SiC brick with% 26 α - SiC as the skeleton and fine grain% 26 β - SiC as the matrix is produced 26 β - SiC is formed by the reaction of fine silicon powder and fine carbon powder during the firing process, and this product also contains a small amount of residual silicon and carbon.
(3) Silicon oxynitride combined with silicon carbide brick: When preparing this brick, the proportion of fine silicon powder should be less than that of silicon carbide.